The order Sirenia is composed of manatees and dugongs, and the order Cetacea includes whales, dolphins, and porpoises.

However, in a phylogenetic analysis of the complete mitochondrial genome of the Jamaican fruit bat it appeared more closely related to cetferungulates, a clade including Cetacea, Artiodactyla, Perissodactyla, and Carnivora.

The order Cetacea comprises two extant sub-orders and one extinct sub-order.